2,3-Dibromo-1,3-bis­(4-fluoro­phen­yl)propan-1-one

Jasinski, J.P.; Guild, C.J.; Samshuddin, S.; Narayana, B.; Yathirajan, H.S.

doi:10.1107/S1600536810026905

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 66| Part 8| August 2010| Page o2018

https://doi.org/10.1107/S1600536810026905

Open

access

2,3-Dibromo-1,3-bis(4-fluorophenyl)propan-1-one

Jerry P. Jasinski,^a ^* Curtis J Guild,^a S. Samshuddin,^b B. Narayana ^b and H. S. Yathirajan ^c

^aDepartment of Chemistry, Keene State College, 229 Main Street, Keene, NH 03435-2001, USA, ^bDepartment of Studies in Chemistry, Mangalore University, Mangalagangotri 574 199, India, and ^cDepartment of Studies in Chemistry, University of Mysore, Manasagangotri, Mysore 570 006, India
^*Correspondence e-mail: jjasinski@keene.edu

(Received 4 July 2010; accepted 7 July 2010; online 14 July 2010)

In the title compound, C₁₅H₁₀Br₂F₂O, the dihedral angle between the two 3-fluoro-substituted benzene rings is 5.7 (5)°. The two bromine substituents on the chalcone moiety are close to anti as the Br—C—C—Br torsion angle is 176.9 (7)°. Weak C—Br⋯π interactions may contribute to the crystal stability.

Related literature

For bromo substitution of non-linerar optical (NLO) compounds, see: Uchida et al. (1998 ); Tam et al. (1989 ); Indira et al. (2002 ). For NLO first-order hyperpolarizabilities, see: Zhao et al. (2002 ). For related structures, see: Narayana et al. (2007 ); Sarojini et al. (2007 ); Yathirajan et al. (2007 ); Butcher et al. (2006 ).

Experimental

Crystal data

C₁₅H₁₀Br₂F₂O
M_r = 404.05
Triclinic, $[P \overline 1]$
a = 5.7381 (13) Å
b = 9.909 (2) Å
c = 12.575 (3) Å
α = 75.324 (3)°
β = 87.472 (3)°
γ = 82.300 (3)°
V = 685.4 (3) Å³
Z = 2
Mo Kα radiation
μ = 5.93 mm⁻¹
T = 100 K
0.55 × 0.30 × 0.25 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2008 ) T_min = 0.329, T_max = 0.746
8841 measured reflections
4008 independent reflections
3408 reflections with I > 2σ(I)
R_int = 0.032

Refinement

R[F² > 2σ(F²)] = 0.031
wR(F²) = 0.079
S = 1.21
4008 reflections
181 parameters
H-atom parameters constrained
Δρ_max = 1.08 e Å⁻³
Δρ_min = −0.87 e Å⁻³

Table 1
Y—X⋯Cg interactions (Å)

Cg1 and Cg2 are the centroids of the C1–C6 and C10–C15 rings, respectively.

Y—X⋯Cg	X⋯Cg	Y⋯Cg	Y—X⋯Cg
C8—Br1⋯Cg1ⁱ	3.650 (7)	5.617 (2)	174
C7—Br3⋯Cg2ⁱⁱ	3.479 (6)	5.341 (1)	153
Symmetry codes: (i) −x, 1 − y, 1 − z; (ii) 1 − x, 1 − y, −z.

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S1600536810026905/tk2690sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810026905/tk2690Isup2.hkl

checkCIF report

Comment top

The non-linear optical (NLO) effect in organic molecules originates from a strong donor–acceptor intermolecular interaction, a delocalized π-electron system and the ability to crystallize in a non-centrosymmetric space group. Among several organic compounds exhibiting NLO effects, chalcone derivatives are important materials known for their excellent blue light transmittance and good crystallizability. It has been observed that substitution of a bromo group on either of the phenyl rings greatly influences non-centrosymmetric crystal packing (Uchida et al., 1998; Tam et al., 1989; Indira et al., 2002). Bromo substituents can obviously improve molecular first-order hyperpolarizabilities and can effectively reduce dipole–dipole interactions between molecules (Zhao et al., 2002). Chalcone derivatives usually have lower melting points, which can be a drawback when their crystals are used in optical instruments. Chalcone dibromides usually have higher melting points and are thermally stable.

The crystal structures of some dibromo chalcones viz., 2,3-dibromo- 3-(5-bromo-2-methoxyphenyl)-1-(2,4-dichlorophenyl)propan-1-one (Narayana et al., 2007), 2,3-dibromo-3-(4-bromo-6-methoxy-2 -naphthyl)-1-(4-methoxyphenyl)propan-1-one (Sarojini et al., 2007), 2,3-dibromo-1-(3-bromo-2-thienyl)-3-(4-fluorophenyl)propan-1-one, (Yathirajan et al., 2007), 2,3-dibromo-1-(4-methoxyphenyl)-3-[4- (methylsulfanyl)phenyl] propan-1-one, (Butcher et al., 2006) have been reported. In continuation of our studies on chalcones and their derivatives, the title chalcone dibromide, C₁₅H₁₀F₂Br₂O, was prepared by the bromination of the chalcone precursor, and its crystal structure is reported.

The title compound, C₁₅H₁₀F₂Br₂O, contains two m-fluoro-substituted rings attached to a brominated chalcone moiety. The dihedral angle between the mean planes of the benzene rings is 5.7 (5) °. The two bromine substituents on the chalcone moiety are nearly opposite to each orher [Br1–C8–C7–Br2 = 176.9 (7) °]. Weak C—Br···π interactions (Table 1) contribute to crystal stability.

Related literature top

For bromo substitution of non-linerar optical (NLO) compounds, see: Uchida et al. (1998); Tam et al. (1989); Indira et al. (2002). For NLO first-order hyperpolarizabilities, see: Zhao et al. (2002). For related structures, see: Narayana et al. (2007); Sarojini et al. (2007); Yathirajan et al. (2007); Butcher et al. (2006).

Experimental top

To a solution of (2E)-1,3-bis(4-fluorophenyl)prop-2-en-1-one (2.44 g, 0.01 mol) in acetic acid (25 ml), bromine (1.60 g, 0.01 mol) in acetic acid (10 ml) was added slowly with stirring at 273 K. After completion of the addition of the bromine solution, the reaction mixture was stirred for 5 h. The solid obtained was filtered and recrystallized from acetone. The crystals were grown from methanol by slow evaporation and the yield of the compound was 86%. (m.pt. 443 K). Analytical data: Found (Calculated): C %: 44.57 (44.59); H%: 2.48 (2.49).

Structure description top

For bromo substitution of non-linerar optical (NLO) compounds, see: Uchida et al. (1998); Tam et al. (1989); Indira et al. (2002). For NLO first-order hyperpolarizabilities, see: Zhao et al. (2002). For related structures, see: Narayana et al. (2007); Sarojini et al. (2007); Yathirajan et al. (2007); Butcher et al. (2006).

Computing details top

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

Fig. 1. Molecular structure of C₁₅H₁₀F₂Br₂O, showing the atom labeling scheme and 50% probability displacement ellipsoids.

2,3-Dibromo-1,3-bis(4-fluorophenyl)propan-1-one top

Crystal data top

C₁₅H₁₀Br₂F₂O	Z = 2
M_r = 404.05	F(000) = 392
Triclinic, P1	D_x = 1.958 Mg m⁻³
Hall symbol: -P 1	Melting point: 443 K
a = 5.7381 (13) Å	Mo Kα radiation, λ = 0.71073 Å
b = 9.909 (2) Å	Cell parameters from 3859 reflections
c = 12.575 (3) Å	θ = 2.4–31.2°
α = 75.324 (3)°	µ = 5.93 mm⁻¹
β = 87.472 (3)°	T = 100 K
γ = 82.300 (3)°	Block, colourless
V = 685.4 (3) Å³	0.55 × 0.30 × 0.25 mm

Data collection top

Bruker APEXII CCD diffractometer	4008 independent reflections
Radiation source: fine-focus sealed tube	3408 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.032
ω scans	θ_max = 31.1°, θ_min = 2.1°
Absorption correction: multi-scan (SADABS; Bruker, 2008)	h = −8→8
T_min = 0.329, T_max = 0.746	k = −14→14
8841 measured reflections	l = −17→17

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.031	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.079	H-atom parameters constrained
S = 1.21	w = 1/[σ²(F_o²) + (0.0334P)²] where P = (F_o² + 2F_c²)/3
4008 reflections	(Δ/σ)_max = 0.001
181 parameters	Δρ_max = 1.08 e Å⁻³
0 restraints	Δρ_min = −0.87 e Å⁻³

Crystal data top

C₁₅H₁₀Br₂F₂O	γ = 82.300 (3)°
M_r = 404.05	V = 685.4 (3) Å³
Triclinic, P1	Z = 2
a = 5.7381 (13) Å	Mo Kα radiation
b = 9.909 (2) Å	µ = 5.93 mm⁻¹
c = 12.575 (3) Å	T = 100 K
α = 75.324 (3)°	0.55 × 0.30 × 0.25 mm
β = 87.472 (3)°

Data collection top

Bruker APEXII CCD diffractometer	4008 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2008)	3408 reflections with I > 2σ(I)
T_min = 0.329, T_max = 0.746	R_int = 0.032
8841 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.031	0 restraints
wR(F²) = 0.079	H-atom parameters constrained
S = 1.21	Δρ_max = 1.08 e Å⁻³
4008 reflections	Δρ_min = −0.87 e Å⁻³
181 parameters

Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Br1	0.01364 (4)	0.64928 (2)	0.325242 (18)	0.01732 (7)
Br3	0.63722 (4)	0.41938 (2)	0.166955 (18)	0.01767 (7)
F3	0.2805 (3)	0.01545 (14)	0.61742 (12)	0.0256 (3)
F4	−0.1808 (3)	0.97463 (15)	−0.24671 (12)	0.0269 (3)
O1	0.4729 (3)	0.76521 (17)	0.16467 (14)	0.0197 (3)
C1	0.1701 (4)	0.1693 (2)	0.44729 (19)	0.0198 (5)
H1	0.0491	0.1177	0.4421	0.024*
C2	0.3155 (4)	0.1313 (2)	0.53742 (19)	0.0177 (5)
C3	0.4942 (4)	0.2065 (2)	0.5500 (2)	0.0199 (5)
H3	0.5871	0.1797	0.6124	0.024*
C4	0.5301 (4)	0.3239 (2)	0.46579 (19)	0.0189 (5)
H4	0.6503	0.3759	0.4716	0.023*
C5	0.3885 (4)	0.3646 (2)	0.37295 (18)	0.0157 (4)
C6	0.2097 (4)	0.2867 (2)	0.36490 (19)	0.0188 (5)
H6	0.1147	0.3136	0.3031	0.023*
C7	0.4417 (4)	0.4886 (2)	0.28267 (18)	0.0152 (4)
H7	0.5313	0.5473	0.3131	0.018*
C24	−0.1493 (4)	0.7950 (2)	−0.08429 (19)	0.0180 (4)
H24	−0.2841	0.7630	−0.1019	0.022*
C25	−0.0292 (4)	0.7287 (2)	0.01293 (18)	0.0150 (4)
H25	−0.0851	0.6520	0.0613	0.018*
C26	0.1738 (4)	0.7767 (2)	0.03802 (18)	0.0133 (4)
C27	0.2560 (4)	0.8922 (2)	−0.03527 (18)	0.0146 (4)
H27	0.3918	0.9243	−0.0188	0.018*
C28	0.1387 (4)	0.9599 (2)	−0.13229 (19)	0.0178 (5)
H28	0.1938	1.0366	−0.1811	0.021*
C29	−0.0623 (4)	0.9097 (2)	−0.15370 (18)	0.0176 (5)
C30	0.3079 (4)	0.7134 (2)	0.14074 (18)	0.0146 (4)
C31	0.2346 (4)	0.5802 (2)	0.22021 (18)	0.0155 (4)
H31	0.1558	0.5266	0.1802	0.019*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br1	0.01593 (12)	0.01512 (11)	0.02036 (13)	0.00004 (8)	0.00191 (8)	−0.00485 (8)
Br3	0.01936 (12)	0.01393 (11)	0.02088 (13)	−0.00394 (8)	0.00569 (9)	−0.00655 (8)
F3	0.0373 (9)	0.0182 (7)	0.0176 (7)	−0.0072 (6)	0.0014 (6)	0.0037 (5)
F4	0.0366 (9)	0.0234 (7)	0.0175 (7)	0.0027 (6)	−0.0117 (6)	−0.0004 (6)
O1	0.0211 (8)	0.0162 (7)	0.0228 (9)	−0.0080 (6)	−0.0057 (7)	−0.0027 (6)
C1	0.0231 (12)	0.0161 (10)	0.0205 (12)	−0.0076 (9)	0.0003 (9)	−0.0027 (9)
C2	0.0228 (12)	0.0128 (10)	0.0153 (10)	−0.0001 (8)	0.0022 (8)	−0.0009 (8)
C3	0.0228 (12)	0.0180 (11)	0.0171 (11)	0.0004 (9)	−0.0052 (9)	−0.0015 (9)
C4	0.0208 (11)	0.0172 (10)	0.0193 (11)	−0.0033 (8)	−0.0035 (9)	−0.0048 (9)
C5	0.0194 (11)	0.0122 (9)	0.0151 (10)	−0.0018 (8)	−0.0002 (8)	−0.0026 (8)
C6	0.0220 (11)	0.0165 (10)	0.0168 (11)	−0.0048 (8)	−0.0046 (9)	−0.0004 (8)
C7	0.0159 (10)	0.0138 (9)	0.0170 (11)	−0.0023 (8)	−0.0003 (8)	−0.0057 (8)
C24	0.0165 (11)	0.0177 (10)	0.0213 (12)	−0.0017 (8)	−0.0026 (9)	−0.0074 (9)
C25	0.0171 (10)	0.0132 (9)	0.0150 (10)	−0.0036 (8)	0.0010 (8)	−0.0035 (8)
C26	0.0166 (10)	0.0099 (9)	0.0134 (10)	−0.0002 (7)	−0.0001 (8)	−0.0036 (7)
C27	0.0164 (10)	0.0107 (9)	0.0181 (11)	−0.0026 (8)	0.0029 (8)	−0.0061 (8)
C28	0.0257 (12)	0.0111 (9)	0.0150 (11)	−0.0011 (8)	0.0018 (9)	−0.0013 (8)
C29	0.0234 (11)	0.0145 (10)	0.0134 (10)	0.0061 (8)	−0.0028 (8)	−0.0046 (8)
C30	0.0170 (10)	0.0110 (9)	0.0163 (10)	−0.0030 (8)	−0.0011 (8)	−0.0036 (8)
C31	0.0188 (11)	0.0127 (9)	0.0151 (10)	−0.0041 (8)	−0.0019 (8)	−0.0022 (8)

Geometric parameters (Å, º) top

Br1—C31	1.974 (2)	C7—C31	1.511 (3)
Br3—C7	2.001 (2)	C7—H7	0.9800
F3—C2	1.352 (2)	C24—C29	1.383 (3)
F4—C29	1.347 (2)	C24—C25	1.395 (3)
O1—C30	1.218 (3)	C24—H24	0.9300
C1—C2	1.380 (3)	C25—C26	1.392 (3)
C1—C6	1.384 (3)	C25—H25	0.9300
C1—H1	0.9300	C26—C27	1.398 (3)
C2—C3	1.383 (3)	C26—C30	1.484 (3)
C3—C4	1.392 (3)	C27—C28	1.389 (3)
C3—H3	0.9300	C27—H27	0.9300
C4—C5	1.394 (3)	C28—C29	1.378 (3)
C4—H4	0.9300	C28—H28	0.9300
C5—C6	1.386 (3)	C30—C31	1.537 (3)
C5—C7	1.502 (3)	C31—H31	0.9800
C6—H6	0.9300

C2—C1—C6	118.1 (2)	C25—C24—H24	120.9
C2—C1—H1	121.0	C24—C25—C26	120.4 (2)
C6—C1—H1	121.0	C24—C25—H25	119.8
F3—C2—C1	118.4 (2)	C26—C25—H25	119.8
F3—C2—C3	118.5 (2)	C25—C26—C27	119.3 (2)
C1—C2—C3	123.0 (2)	C25—C26—C30	123.47 (19)
C2—C3—C4	117.6 (2)	C27—C26—C30	117.3 (2)
C2—C3—H3	121.2	C28—C27—C26	121.2 (2)
C4—C3—H3	121.2	C28—C27—H27	119.4
C5—C4—C3	120.9 (2)	C26—C27—H27	119.4
C5—C4—H4	119.5	C29—C28—C27	117.7 (2)
C3—C4—H4	119.5	C29—C28—H28	121.1
C6—C5—C4	119.2 (2)	C27—C28—H28	121.1
C6—C5—C7	122.1 (2)	F4—C29—C28	118.8 (2)
C4—C5—C7	118.6 (2)	F4—C29—C24	118.0 (2)
C1—C6—C5	121.1 (2)	C28—C29—C24	123.2 (2)
C1—C6—H6	119.5	O1—C30—C26	121.82 (19)
C5—C6—H6	119.5	O1—C30—C31	118.95 (19)
C5—C7—C31	116.96 (19)	C26—C30—C31	119.22 (19)
C5—C7—Br3	108.97 (15)	C7—C31—C30	111.97 (19)
C31—C7—Br3	103.93 (16)	C7—C31—Br1	108.95 (16)
C5—C7—H7	108.9	C30—C31—Br1	105.03 (14)
C31—C7—H7	108.9	C7—C31—H31	110.3
Br3—C7—H7	108.9	C30—C31—H31	110.3
C29—C24—C25	118.2 (2)	Br1—C31—H31	110.3
C29—C24—H24	120.9

C6—C1—C2—F3	−178.9 (2)	C30—C26—C27—C28	−178.6 (2)
C6—C1—C2—C3	1.5 (4)	C26—C27—C28—C29	0.3 (3)
F3—C2—C3—C4	178.8 (2)	C27—C28—C29—F4	179.2 (2)
C1—C2—C3—C4	−1.5 (4)	C27—C28—C29—C24	−0.9 (4)
C2—C3—C4—C5	0.8 (4)	C25—C24—C29—F4	−179.1 (2)
C3—C4—C5—C6	0.0 (4)	C25—C24—C29—C28	1.1 (4)
C3—C4—C5—C7	−177.5 (2)	C25—C26—C30—O1	−173.5 (2)
C2—C1—C6—C5	−0.6 (4)	C27—C26—C30—O1	5.2 (3)
C4—C5—C6—C1	−0.1 (4)	C25—C26—C30—C31	5.4 (3)
C7—C5—C6—C1	177.4 (2)	C27—C26—C30—C31	−175.9 (2)
C6—C5—C7—C31	36.4 (3)	C5—C7—C31—C30	172.58 (18)
C4—C5—C7—C31	−146.1 (2)	Br3—C7—C31—C30	−67.3 (2)
C6—C5—C7—Br3	−81.0 (2)	C5—C7—C31—Br1	56.8 (2)
C4—C5—C7—Br3	96.5 (2)	Br3—C7—C31—Br1	176.97 (9)
C29—C24—C25—C26	−0.6 (3)	O1—C30—C31—C7	−31.3 (3)
C24—C25—C26—C27	0.0 (3)	C26—C30—C31—C7	149.7 (2)
C24—C25—C26—C30	178.7 (2)	O1—C30—C31—Br1	86.8 (2)
C25—C26—C27—C28	0.1 (3)	C26—C30—C31—Br1	−92.2 (2)

Experimental details

Crystal data
Chemical formula	C₁₅H₁₀Br₂F₂O
M_r	404.05
Crystal system, space group	Triclinic, P1
Temperature (K)	100
a, b, c (Å)	5.7381 (13), 9.909 (2), 12.575 (3)
α, β, γ (°)	75.324 (3), 87.472 (3), 82.300 (3)
V (Å³)	685.4 (3)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	5.93
Crystal size (mm)	0.55 × 0.30 × 0.25

Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2008)
T_min, T_max	0.329, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections	8841, 4008, 3408
R_int	0.032
(sin θ/λ)_max (Å⁻¹)	0.727

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.031, 0.079, 1.21
No. of reflections	4008
No. of parameters	181
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	1.08, −0.87

Computer programs: APEX2 (Bruker, 2008), SAINT (Bruker, 2008), SHELXTL (Sheldrick, 2008).

Y—X···Cg interactions (Å) top

Cg1 and Cg2 are the centroids of the C1–C6 and C10–C15 rings, respectively.

Y—X···Cg	X···Cg	Y···Cg	Y—X···Cg
C8—Br1···Cg1ⁱ	3.650 (7)	5.617 (2)	174
C7—Br3···Cg2ⁱⁱ	3.479 (6)	5.341 (1)	153

Symmetry codes: (i) -x, 1-y, 1-z ; (ii) 1-x, 1-y, -z.

Acknowledgements

JPJ thanks Dr Matthias Zeller and the YSU Department of Chemistry for their assistance with the data collection. The diffractometer was funded by NSF grant 0087210, by Ohio Board of Regents grant CAP-491, and by YSU. SS thanks Mangalore University and the UGC SAP for financial assistance for the purchase of chemicals. HSY thanks the UOM for sabbatical leave.

References

Bruker (2008). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Butcher, R. J., Yathirajan, H. S., Sarojini, B. K., Narayana, B. & Mithun, A. (2006). Acta Cryst. E62, o1629–o1630. Web of Science CSD CrossRef IUCr Journals Google Scholar
Indira, J., Karat, P. P. & Sarojini, B. K. (2002). J. Cryst. Growth, 242, 209–214. Web of Science CrossRef CAS Google Scholar
Narayana, B., Mayekar, A. N., Yathirajan, H. S., Sarojini, B. K. & Kubicki, M. (2007). Acta Cryst. E63, o4362. Web of Science CSD CrossRef IUCr Journals Google Scholar
Sarojini, B. K., Narayana, B., Yathirajan, H. S., Mayekar, A. N. & Bolte, M. (2007). Acta Cryst. E63, o3755. Web of Science CSD CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Tam, W., Guerin, B., Calabrese, J. C. & Stevenson, S. H. (1989). Chem. Phys. Lett. 154, 93–96. CSD CrossRef CAS Web of Science Google Scholar
Uchida, T., Kozawa, K., Sakai, T., Aoki, M., Yoguchi, H., Abduryim, A. & Watanabe, Y. (1998). Mol. Cryst. Liq. Cryst. 315, 135–140. Web of Science CrossRef Google Scholar
Yathirajan, H. S., Vijesh, A. M., Narayana, B., Sarojini, B. K. & Bolte, M. (2007). Acta Cryst. E63, o2198–o2199. Web of Science CSD CrossRef IUCr Journals Google Scholar
Zhao, B., Lu, W. Q., Zhou, Z. H. & Wu, Y. (2002). J. Mater. Chem. 10, 1513–1517. Web of Science CrossRef Google Scholar